[bio] cells Flashcards
what is a cell?
a basic unit of structure and function. it is the simplest unit with all characteristics of life
what are phospholipids?
a major component of biological membranes
special thing about phospholipids in cell membranes?
made up of two layers of phospholipids - phospholipid bilayer
why is phospholipid bilayer?
phospholipid tail is hydrophobic, needs the hydrophilic head to be facing outwards in contact with the extra cellular fluid outside the phospholipid bilayer
why is the cell membrane fluid
phospholipids and proteins are not stationary but can move rapidly across the surface of the membrane
why is the cell membrane mosaic
many different protein molecules are randomly scattered and embedded throughout the phospholipid bilayer
why are cell membranes partially permeable?
due to the nature of the phospholipids, only small hydrophobic molecules can pass through the phospholipid bilayer. as such, for hydrophilic or water-soluble molecules are unable to pass through the cell membrane, transport proteins are required.
what do you mean by partially permeable?
cell membrane only allows certain substances to pass through it
functions of partially permeable cell membrane
it functions to separate and protects a cell from its surrounding environment and controls how substances move in and out of the cell
what does cytoplasm contain
- cytosol
- cytoskeleton
- organelles
what is cytosol?
aqueous solution of essential ions, soluble proteins and soluble organic compounds such as sugars and amino acids
what is cytoskeleton?
network of protein fibres that give support, motility and regulation to the cell
what is organelles?
structures with specialised functions, suspended in the cytosol
what is cytoplasmic streaming
the movement of the fluid substance within a plant or animal cell
how does cytoplasmic streaming help?
aids in the transport of materials and organelles around the cell
structure of nucleus
largest organelle within the eukaryotic cell, usually spherical
what does the nucleus contains
- nuclear envelope
- nucleolus
- dna
what does nuclear envelope do
separates nucleus from the cytoplasm
what does nucleolus do
synthesise ribosomes
where are nucleus found
in almost all eukaryotic cells, except matured red blood cells
function of nucleus
- contains the hereditary material (dna)
- controls activities of the cell